A disorder hopping model for carriers recombination at organic/organic interface (OOI) in double-layer organic light emitting diodes (OLEDs) was presented. According to the structure of an OOI as well as spatial and energetic disorder of hopping states, it was more reasonable to use the disorder hopping model than to use the Fowler-Nordheim formalism. It was shown that the carriers hopping distance, the effective barrier height and the electric field contribution had heavy effects on recombination efficiency. Firstly, when the applied voltage was less than 19.5V (in double-layer OLEDs ITO/α-NPD/Alq3/Al), recombination efficiency increased with the increase of hopping distance, while the applied voltage was larger than 19.5V, it decreased with the increase of hopping distance; secondly, it also increased with the increase of effective barrier height at OOI; Finally, it increased with the increase of differences of electric field at OOI, while it decreased when the value of differences of electric field reached 24×105V/cm. These results were consistent with some experiments.